CN113167847A

CN113167847A - Magnetic sensor array with dual TMR film

Info

Publication number: CN113167847A
Application number: CN202080006972.5A
Authority: CN
Inventors: 郑元凯; C·凯撒; 刁治涛; 胡志清; 钱震中; 王勇鸿; 万渡江; 周荣辉; 毛明; 姜明; D·毛里
Original assignee: Western Digital Technologies Inc
Current assignee: Western Digital Technologies Inc
Priority date: 2019-08-27
Filing date: 2020-03-21
Publication date: 2021-07-23
Anticipated expiration: 2040-03-21
Also published as: EP4022326A4; WO2021040800A1; CN113167847B; US20210063504A1; US11385305B2; EP4022326A1

Abstract

A Tunneling Magnetoresistive (TMR) sensor device including one or more TMR sensors is disclosed. The TMR sensor device includes: a first resistor including a first TMR film; a second resistor including a second TMR film different from the first TMR film; a third resistor including the second TMR film; and a fourth resistor including the first TMR film. The first TMR film includes a reference layer having a first magnetization direction antiparallel to a second magnetization direction of the pinned layer. The second TMR film includes a reference layer having a first magnetization direction parallel to a second magnetization direction of the first pinned layer, and a second pinned layer having a third magnetization direction antiparallel to the first magnetization direction of the reference layer and the second magnetization direction of the first pinned layer.

Description

Magnetic sensor array with dual TMR film

Cross Reference to Related Applications

This application claims priority to U.S. patent application 16/718667 filed on 18.12.2019, which claims benefit of U.S. provisional patent application serial No. 62/892391 filed on 27.8.2019, which is incorporated herein by reference in its entirety.

Background

Technical Field

Embodiments of the present disclosure generally relate to tunneling magnetoresistive sensor devices, such as wheatstone bridge arrays, and methods of making the same.

Description of the related Art

A wheatstone bridge is a circuit for measuring an unknown resistance by balancing two legs of a bridge circuit, one of which contains an unknown component. Compared to a simple voltage divider, a wheatstone circuit provides extremely accurate measurements.

The wheatstone bridge comprises a plurality of resistors, in particular recently magnetic materials such as magnetic sensors. The magnetic sensors may include hall effect magnetic sensors, anisotropic magnetoresistive sensors (AMR), Giant Magnetoresistive (GMR) sensors, and Tunneling Magnetoresistive (TMR) sensors. TMR sensors have a very high sensitivity compared to other magnetic sensors.

A typical Wheatstone bridge comprises four resistors, wherein the first and fourth resistors each comprise a free layer having a magnetization direction disposed at +45 to the magnetization direction of the pinned layer, and the second and third resistors each comprise a free layer having a magnetization direction disposed at-45 to the magnetization direction of the pinned layer. All four resistors are constructed of the same material or film and, as such, the pinned layers of each of the four resistors have the same magnetization direction.

When a magnetic field is applied to the wheatstone bridge, the first and fourth resistors increase with the applied magnetic field and the second and third resistors decrease with the applied magnetic field. However, this design can only utilize half of the magnetoresistance variation due to ± 45 ° between the magnetization directions of the free layer and the pinned layer. Other wheatstone bridge designs result in reduced output voltage or limited sensitivity.

Accordingly, there is a need in the art for a magnetic sensor and method of making the same that operates over the full range of magnetic resistance while achieving maximum output voltage or sensitivity.

Disclosure of Invention

A TMR sensor device including one or more TMR sensors is disclosed. The wheatstone bridge array includes: a first resistor including a first TMR film; a second resistor including a second TMR film different from the first TMR film; a third resistor including the second TMR film; and a fourth resistor including the first TMR film. The first TMR film includes a reference layer having a first magnetization direction antiparallel to a second magnetization direction of the pinned layer. The second TMR film includes a reference layer having a first magnetization direction parallel to a second magnetization direction of the first pinned layer, and a second pinned layer having a third magnetization direction antiparallel to the first magnetization direction of the reference layer and the second magnetization direction of the first pinned layer.

In one embodiment, a TMR sensor device includes at least one TMR sensor including a first TMR film including a first reference layer having a first magnetization direction and a first pinned layer having a second magnetization direction, the first magnetization direction of the first reference layer being antiparallel to the second magnetization direction of the first pinned layer, wherein the first pinned layer includes a Co/CoFe/Co multilayer stack having a thickness of about 20 angstroms to about 30 angstroms, and wherein the first reference layer includes a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms, and at least one TMR sensor including a second TMR film including a second reference layer having a first third magnetization direction, a first second pinned layer having the first third magnetization direction, and a second third pinned layer having a second fourth magnetization direction, the second reference layer and the first third magnetization direction of the first second pinned layer being antiparallel to the second fourth magnetization direction of the second third pinned layer, wherein the second pinned layer comprises a Co/CoFe/Co multilayer stack having a thickness of about 20 angstroms to about 30 angstroms, wherein the third pinned layer comprises a Co/CoFe/Co multilayer stack having a thickness of about 35 angstroms to about 55 angstroms, and wherein the second reference layer comprises a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms.

In another embodiment, a TMR sensor device includes a first resistor including a first TMR film, the first TMR film including a first reference layer having a first magnetization direction, wherein the first reference layer includes a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms; including a second resistor comprising a second TMR film comprising a second reference layer having a second magnetization direction, wherein the second reference layer comprises a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms, and wherein the first magnetization direction of the first reference layer of the first TMR film is anti-parallel to the second magnetization direction of the second reference layer of the second TMR film; a third resistor including a second TMR film; and a fourth resistor including the first TMR film.

In another embodiment, a method of fabricating a TMR sensor device having a first resistor, a second resistor, a third resistor, and a fourth resistor includes forming a first TMR film by depositing a first seed layer, depositing a first antiferromagnetic layer on the first seed layer, depositing a first pinning layer on the first antiferromagnetic layer, the first pinned layer includes a Co/CoFe/Co multilayer stack having a thickness of about 20 angstroms to about 30 angstroms, depositing a first spacer layer over the first pinned layer, depositing a first reference layer over the first spacer layer, the first reference layer comprises a multilayer stack of CoFe/Ta/CoFeB/CoFe having a thickness of about 21 angstroms to about 37 angstroms, depositing a first barrier layer on the first reference layer and a first free layer on the first barrier layer, magnetically annealing the first TMR film to change a first magnetization direction of the first reference layer to be antiparallel to a second magnetization direction of the first pinned layer; forming a second TMR film by depositing a second seed layer, depositing a second antiferromagnetic layer on the second seed layer, depositing a second pinning layer on the second antiferromagnetic layer, the second pinning layer comprising a Co/CoFe/Co multilayer stack having a thickness of about 20 to about 30 angstroms, depositing a second spacer layer on the second pinning layer, depositing a third pinning layer on the second spacer layer, the third pinning layer comprising a Co/CoFe/Co multilayer stack having a thickness of about 35 to about 55 angstroms, depositing a third spacer layer on the third pinning layer, depositing a second reference layer on the third spacer layer, the second reference layer comprising a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 to about 37 angstroms, depositing a second barrier layer on the second reference layer, and depositing a second free layer on the second barrier layer, magnetically annealing the second TMR film to change a third magnetization direction of the third pinned layer to the reference layer with the second free layer A fourth magnetization direction is antiparallel, wherein the first magnetization direction of the first reference layer of the first TMR film is antiparallel to the fourth magnetization direction of the second reference layer of the second TMR film, the first resistor and the fourth resistor are formed by the first TMR film, and the second resistor and the third resistor are formed by the second TMR film, wherein the first resistor is adjacent to the second resistor and the third resistor, the second resistor is adjacent to the first resistor and the fourth resistor, the third resistor is adjacent to the first resistor and the fourth resistor, and the fourth resistor is adjacent to the second resistor and the third resistor.

Drawings

So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

Fig. 1 shows a schematic diagram of a TMR sensor device.

Fig. 2 shows a schematic diagram of a first TMR film and a second TMR film for forming a resistor of a TMR sensor device according to an embodiment.

Fig. 3A-3B illustrate a first TMR film, or TMR film a, at various stages of formation according to one embodiment.

Fig. 4A to 4B show a second TMR film or TMR film B in various stages of formation according to another embodiment.

Fig. 5A to 5B show graphs of output signals of the first TMR film and the second TMR film with an applied external field.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

Detailed Description

Hereinafter, reference is made to embodiments of the present disclosure. It should be understood, however, that the disclosure is not limited to the specifically described embodiments. Rather, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the present disclosure. Moreover, although embodiments of the disclosure may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not a limitation of the disclosure. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to "the disclosure" should not be construed as a generalization of any inventive subject matter disclosed herein and should not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).

A Tunneling Magnetoresistive (TMR) sensor device including one or more TMR sensors is disclosed. The wheatstone bridge array includes: a first resistor including a first TMR film; a second resistor including a second TMR film different from the first TMR film; a third resistor including the second TMR film; and a fourth resistor including the first TMR film. The first TMR film includes a reference layer having a first magnetization direction antiparallel to a second magnetization direction of the pinned layer. The second TMR film includes a reference layer having a first magnetization direction parallel to a second magnetization direction of the first pinned layer, and a second pinned layer having a third magnetization direction antiparallel to the first magnetization direction of the reference layer and the second magnetization direction of the first pinned layer.

Fig. 1 is a schematic diagram of a TMR sensor device 100 designed as a wheatstone bridge array. TMR sensor device 100 includes bias source 102, first resistor 104, second resistor 106, third resistor 108, fourth resistor 110, first sensor 112, second sensor 114, and ground connection 116. A bias voltage is applied across the array from bias source 102 to ground connection 116. The first sensor 112 and the second sensor 114 sense the output of the applied voltage. Any temperature changes from the

resistors

104, 106, 108, 110 can be cancelled out.

As discussed herein, the

resistors

104, 106, 108, 110 each comprise a TMR sensor. In one embodiment, the TMR sensors are each unique and different such that the

resistors

104, 106, 108, 110 have different resistances. In another embodiment, the TMR sensors are the same, but the

resistors

104, 106, 108, 110 are different. In yet another embodiment,

resistors

104, 110 are identical to each other (because the TMR

sensors comprising resistors

104, 110 are identical to each other), and

resistors

106, 108 are identical to each other (because the TMR

sensors comprising resistors

106, 108 are identical to each other) but different from

resistors

104, 110. For a TMR sensor in TMR sensor device 100, RA of array 100 is about 100 ohms/square micron.

Fig. 2 is a schematic diagram illustrating a first TMR film 220 and a second TMR film 230 for forming

resistors

202, 204, 206, 208 of a TMR-based magnetic sensor or TMR sensor device 200 (e.g., a wheatstone bridge array) according to one embodiment. The TMR sensor device 200 may be the TMR sensor device 100 of fig. 1. Each of the

resistors

202, 204, 206, 208 individually operates as a TMR sensor.

As shown in fig. 2, both first resistor R1202 and fourth resistor R4208 include first TMR film 220, and both second resistor R2204 and third resistor R3206 include second TMR film 230. The TMR resistance of the first resistor R1202 and the fourth resistor R4208 formed of the first TMR film 220 increases linearly with an external magnetic field, and the TMR resistance of the second resistor R2204 and the third resistor R3206 formed of the second TMR film 230 decreases linearly with an external magnetic field. Alternatively, the TMR resistance of the first resistor R1202 and the fourth resistor R4208 formed of the first TMR film 220 may linearly decrease with an external magnetic field, and the TMR resistance of the second resistor R2204 and the third resistor R3206 formed of the second TMR film 230 may linearly increase with an external magnetic field. Thus, two

different TMR films

220, 230 provide two different magnetoresistive responses.

Fig. 3A-3B illustrate the first TMR film 220 or TMR film a of fig. 2 at various stages of formation, according to one embodiment. Fig. 3A shows the first TMR film 220 during magnetic annealing, and fig. 3B shows the first TMR film 220 after magnetic annealing. First TMR film 220 may function as one or more TMR sensors. Fig. 3B shows a first TMR film 220 used in the TMR sensor device 200 of fig. 2.

First TMR film 220 includes a Free Layer (FL)302, a barrier layer 304 disposed below and in contact with FL 302, a Reference Layer (RL)306 disposed below and in contact with barrier layer 304, a spacer layer 308 disposed below and in contact with RL 306, a Pinned Layer (PL)310 disposed below and in contact with spacer layer 308, an Antiferromagnetic (AFM) layer 312 disposed below and in contact with PL 310, and a seed layer 314 disposed below and in contact with AFM layer 312. FL 302 may also be referred to as a sensing layer. The first TMR layer 220 has a total thickness of about 120 angstroms to about 630 angstroms.

In one embodiment, the seed layer 314 comprises a conductive material, such as ruthenium, having a thickness of about 10 angstroms to about 100 angstroms, and is deposited by known deposition methods such as electroplating, electroless plating, or sputtering. Additionally, it should be understood that while ruthenium has been illustrated as the seed layer 314 material, other materials are also contemplated, and the embodiments discussed herein are not limited to the use of ruthenium for the seed layer 314.

Suitable materials for the AFM layer 312 include IrMn or PtMn with a thickness of about 40 angstroms to about 100 angstroms. The AFM layer 312 can be formed by well-known deposition methods such as sputtering. Additionally, it should be understood that while IrMn and PtMn have been illustrated as AFM layer 312 materials, other materials are also contemplated, and the embodiments discussed herein are not limited to the use of IrMn or PtMn for AFM layer 312.

Suitable materials for the pinned layer 310 include CoFe or Co/CoFe/Co multilayer stacks having a thickness of about 20 angstroms to about 30 angstroms. In one embodiment, the Co component in the CoFe is about 25% to 70%. The pinned layer 310 may be formed by a known deposition method, such as sputtering. Additionally, it should be understood that while CoFe or Co/CoFe/Co has been illustrated as the pinning layer 310 material, other materials are also contemplated and the embodiments discussed herein are not limited to the use of CoFe or Co/CoFe/Co for the pinning layer 310.

Suitable materials for the spacer layer 308 include Ru having a thickness of about 4 angstroms to about 10 angstroms. The spacer layer 308 can be formed by known deposition methods, such as sputtering. Additionally, it should be understood that while ruthenium has been illustrated as the spacer layer 308 material, other materials are also contemplated, and the embodiments discussed herein are not limited to the use of ruthenium for the spacer layer 308.

Suitable materials for reference layer 306 include CoFe/Ta/CoFeB/CoFe as a multilayer stack having a thickness of about 21 angstroms to about 37 angstroms. The first CoFe layer may have a thickness of about 8 angstroms to about 10 angstroms. In one embodiment, the Co component in the first CoFe layer is about 0% to 25%. The Ta layer may have a thickness of about 0.5 angstroms to about 2 angstroms. The CoFeB layer can have a thickness of about 10 angstroms to about 15 angstroms. In one embodiment, the B component in the CoFeB layer is about 15% to 25%. The second CoFe layer may have a thickness of about 3 angstroms to about 10 angstroms. In one embodiment, the Co component in the second CoFe layer is about 10% to 70%. The reference layer 306 may be formed by known deposition methods, such as sputtering. Additionally, it should be understood that while CoFe/Ta/CoFeB/CoFe has been illustrated as the reference layer 306 material, other materials are also contemplated and the embodiments discussed herein are not limited to the use of CoFe/Ta/CoFeB/CoFe for the reference layer 306.

Suitable materials for barrier layer 304 include MgO having a thickness of about 10 angstroms to about 20 angstroms. It should be understood that although MgO is illustrated as barrier layer 304, other insulating materials are also contemplated.

Suitable materials for the free layer 302 include a CoFe/CoFeB/Ta/NiFe multilayer stack having a thickness of about 16 angstroms to about 332 angstroms. The CoFe layer may have a thickness of about 3 angstroms to about 10 angstroms. The CoFeB layer can have a thickness of about 10 angstroms to about 20 angstroms. The Ta layer may have a thickness of about 0.5 angstroms to about 2 angstroms. The NiFe layer may have a thickness of about 3 angstroms to about 300 angstroms, such as about 3 angstroms to about 10 angstroms or about 10 angstroms to about 300 angstroms. The free layer 302 may be formed by well-known deposition methods, such as sputtering. Additionally, it should be understood that while CoFe/CoFeB/Ta/NiFe has been illustrated as the free layer 302 material, other materials are also contemplated and the embodiments discussed herein are not limited to the use of CoFe/CoFeB/Ta/NiFe for the free layer 302.

Fig. 3A shows the first TMR film 220 during magnetic annealing. After the layers of the first TMR film 220 have been deposited, the first TMR film 220 is annealed at a temperature of about 250 degrees celsius to about 300 degrees celsius and a magnetic field of about 1 tesla to about 5 tesla in a magnetic oven. During magnetic annealing, FL 302 has a magnetization direction 322 that points in the x-direction, RL 306 has a first magnetization direction 324 that points in the x-direction, and PL 310 has a first magnetization direction 326 that points in the x-direction. Thus, during magnetic annealing, magnetization direction 326 of PL 310 is parallel to magnetization direction 322 of FL 302 and parallel to magnetization direction 324 of RL 306.

In FIG. 3B, after magnetic annealing, FL 302 has magnetization direction 322 pointing in the x-direction, RL 306 has second magnetization direction 334 pointing in the x-direction, and PL 310 has first magnetization direction 326 pointing in the x-direction. Thus, during magnetic annealing, magnetization direction 326 of PL 310 is parallel to magnetization direction 322 of FL 302 and anti-parallel to magnetization direction 334 of RL 306.

The magnetization direction 326 of the PL 310 is pinned by the AFM layer 312, so the magnetic moment of the PL 310 does not change when an external field is applied. RL 306 is antiferromagnetically coupled to PL 310 via spacer layer 308. Thus, after magnetic annealing, the magnetization direction of RL 306 is fixed when an external field is applied. FL 302 may be biased when an external field is applied to obtain a linear signal, and the magnetic moment of FL 302 may be further rotated when an external field is applied.

Fig. 4A-4B illustrate second TMR film 230 or TMR film B of fig. 2 at various stages of formation according to one embodiment. Fig. 4A shows second TMR film 230 during magnetic annealing, and fig. 4B shows second TMR film 230 after magnetic annealing. Second TMR film 230 may function as one or more TMR sensors. Fig. 4B shows a second TMR film 230 used in the TMR sensor device 200 of fig. 2.

Second TMR film 230 includes FL 402, barrier layer 404 disposed below and in contact with FL 402, RL 406 disposed below and in contact with barrier layer 404, first spacer layer 408 disposed below and in contact with RL 406, second pinning layer (PL2)416 disposed below and in contact with first spacer layer 408, second spacer layer 418 disposed below and in contact with PL2416, first pinning layer (PL1)410 disposed below and in contact with second spacer layer 418, AFM layer 412 disposed below and in contact with PL1410, and seed layer 414 disposed below and in contact with AFM layer 412. FL 402 may also be referred to as a sensing layer. The second TMR layer 230 has a total thickness of about 155 angstroms to about 1675 angstroms.

In one embodiment, the seed layer 414 comprises a conductive material, such as ruthenium, having a thickness of about 10 angstroms to about 100 angstroms, and is deposited by known deposition methods, such as electroplating, electroless plating, or sputtering. Additionally, it should be understood that while ruthenium has been illustrated as the seed layer 414 material, other materials are also contemplated, and the embodiments discussed herein are not limited to the use of ruthenium for the seed layer 414.

Suitable materials for the AFM layer 412 include IrMn or PtMn with a thickness of about 40 angstroms to about 100 angstroms. The AFM layer 412 can be formed by known deposition methods such as sputtering. Additionally, it should be understood that while IrMn and PtMn have been illustrated as AFM layer 412 materials, other materials are also contemplated and the embodiments discussed herein are not limited to the use of IrMn or PtMn for AFM layer 412.

Suitable materials for first pinned layer 410 include CoFe or Co/CoFe/Co multilayer stacks having a thickness of about 20 angstroms to about 30 angstroms. In one embodiment, the Co component in the CoFe is about 25% to 70%. The first pinning layer 410 may be formed by a known deposition method such as sputtering. Additionally, it should be understood that while CoFe or Co/CoFe/Co has been illustrated as the material of the first pinned layer 410, other materials are also contemplated and the embodiments discussed herein are not limited to the use of CoFe or Co/CoFe/Co for the first pinned layer 410.

Suitable materials for second pinned layer 416 include CoFe or Co/CoFe/Co multilayer stacks having a thickness of about 35 angstroms to about 55 angstroms. Thus, the second pinned layer 416 has a greater thickness in the y-direction than the first pinned layer 410. In one embodiment, the second pinned layer 416 has a thickness in the y-direction that is 1 to 2 times greater than the first pinned layer 410. The first Co layer can be about 5 angstroms thick, the CoFe layer can be about 30 angstroms thick, and the second Co layer can be about 5 angstroms thick. In one embodiment, the Co component in the CoFe layer is about 25% to 70%. The second pinning layer 416 may be formed by a known deposition method (e.g., sputtering). Additionally, it should be understood that while CoFe or Co/CoFe/Co has been illustrated as the material of the second pinned layer 416, other materials are also contemplated and the embodiments discussed herein are not limited to the use of CoFe or Co/CoFe/Co for the second pinned layer 416.

Suitable materials for each of the first and second spacer layers 408, 418 include Ru having a thickness of about 4 angstroms to about 10 angstroms. The first spacer layer 408 and the second spacer layer 418 can be formed by known deposition methods, such as sputtering. Additionally, it should be understood that while ruthenium has been illustrated as the material of the first and second spacer layers 408, 418, other materials are also contemplated and the embodiments discussed herein are not limited to ruthenium for the first and second spacer layers 408, 418.

Suitable materials for reference layer 406 include CoFe/Ta/CoFeB/CoFe as a multilayer stack having a thickness of about 21 angstroms to about 37 angstroms. The first CoFe layer may have a thickness of about 8 angstroms to about 10 angstroms. In one embodiment, the Co component in the first CoFe layer is about 0% to 25%. The Ta layer may have a thickness of about 0.5 angstroms to about 2 angstroms. The CoFeB layer can have a thickness of about 10 angstroms to about 15 angstroms. In one embodiment, the B component in CoFeB is about 15% to 25%. The second CoFe layer may have a thickness of about 3 angstroms to about 10 angstroms. In one embodiment, the Co component in the second CoFe layer is about 10% to 70%. The reference layer 406 may be formed by known deposition methods, such as sputtering. Additionally, it should be understood that while CoFe/Ta/CoFeB/CoFe has been illustrated as the reference layer 406 material, other materials are also contemplated and the embodiments discussed herein are not limited to the use of CoFe/Ta/CoFeB/CoFe for the reference layer 406.

Suitable materials for barrier layer 404 include MgO having a thickness of about 10 angstroms to about 20 angstroms. It should be understood that although MgO is illustrated as barrier layer 404, other insulating materials are also contemplated.

Suitable materials for the free layer 402 include a CoFe/CoFeB/Ta/NiFe multilayer stack having a thickness of about 16 angstroms to about 332 angstroms. The CoFe layer may have a thickness of about 3 angstroms to about 10 angstroms. The CoFeB layer can have a thickness of about 10 angstroms to about 20 angstroms. The Ta layer may have a thickness of about 0.5 angstroms to about 2 angstroms. The NiFe layer may have a thickness of about 3 angstroms to about 300 angstroms, such as about 3 angstroms to about 10 angstroms or about 10 angstroms to about 300 angstroms. The free layer 402 may be formed by known deposition methods, such as sputtering. Additionally, it should be understood that while CoFe/CoFeB/Ta/NiFe has been illustrated as the free layer 402 material, other materials are also contemplated and the embodiments discussed herein are not limited to the use of CoFe/CoFeB/Ta/NiFe for the free layer 402.

Fig. 4A shows the second TMR film 230 during magnetic annealing. After the layers of the second TMR film 230 have been deposited, the second TMR film 230 is annealed at a temperature of about 250 degrees celsius to about 300 degrees celsius and a magnetic field of about 1 tesla to about 5 tesla in a magnetic oven. During magnetic annealing, FL 402 has a magnetization direction 422 pointing in the x-direction, RL 406 has a first magnetization direction 424 pointing in the x-direction, PL1410 has a first magnetization direction 426 pointing in the x-direction, and PL2416 has a first magnetization direction 428 pointing in the x-direction. Thus, during magnetic annealing, the magnetization direction 426 of PL1410 is parallel to the magnetization direction 422 of FL 402 and the magnetization direction 424 of RL 406, and parallel to the magnetization direction 428 of PL 2416.

In FIG. 4B, after magnetic annealing, FL 402 has a magnetization direction 422 pointing in the x-direction, RL 406 has a first magnetization direction 424 pointing in the x-direction, PL1410 has a first magnetization direction 426 pointing in the x-direction, and PL2416 has a second magnetization direction 438 pointing in the x-direction. Thus, after magnetic annealing, the magnetization direction 426 of PL1410 is parallel to the magnetization direction 422 of FL 402 and parallel to the magnetization direction 424 of RL 406. However, the magnetization direction 426 of PL1410 is anti-parallel to the magnetization direction 438 of PL 2418.

The magnetization direction 426 of the PL1410 is pinned by the AFM layer 412, so the magnetic moment of the PL1410 does not change when an external field is applied over the operating field range (e.g., less than 600 Oe). The RL 406 is antiferromagnetically coupled to the PL 410 by a first spacer layer 408. Thus, after magnetic annealing, the magnetization direction of the RL 406 is fixed when an external field is applied over the operating field range (e.g., less than 600 Oe). The FL 402 may be biased when an external field is applied to obtain a linear signal, and the magnetic moment of the FL 402 may be further rotated when an external field is applied.

In comparison with the second TMR film 230 used to form the TMR sensor device 200 of fig. 2, the magnetization direction 322 of the FL 302 of the first TMR film 220 is pointing in the x-direction and parallel to the magnetization direction 422 of the FL 402 of the second film, which is also pointing in the x-direction. The magnetization direction 334 of the RL 306 of the first TMR film 220 is directed in the x-direction and antiparallel to the magnetization direction 424 of the RL 406 of the second TMR film 230, which is directed in the x-direction. The magnetization direction 326 of the PL 310 of the first TMR film 220 is pointing in the x-direction and parallel to the magnetization direction 426 of the PL1410 of the second TMR film 230, which is also pointing in the x-direction. The magnetization direction 438 of the second film's PL 2418 points in the x-direction, is parallel to the magnetization direction 334 of the RL 306 of the first TMR film 220, and is anti-parallel to the magnetization direction 424 of the RL 406 of the second TMR film 230.

Because first TMR film 220 and second TMR film 230 have different RL magnetization directions, the TMR resistance response of each film is equal but opposite (i.e., as one film linearly decreases, the other film linearly increases). Thus, all of the

resistors

202, 204, 206, 208 in the TMR sensor device 200 of fig. 2 can operate in the full magnetoresistance range while achieving a maximum output voltage or sensitivity for a given TMR ratio.

To form TMR sensor device 200 of fig. 2, each of the layers of first TMR film 220 and each of the layers of second TMR film 230 may be deposited separately. The layers of first TMR film 220 and second TMR film 230 may be deposited simultaneously, or a layer of one TMR film may be deposited before a layer of the other TMR film is deposited (e.g., depositing each layer of second TMR film 230, then depositing each layer of first TMR film 220). To form first TMR film 220, seed layer 314 is deposited, AFM layer 312 is deposited on seed layer 314, pinning layer 310 is deposited on AFM layer 312, spacer layer 308 is deposited on pinning layer 310, reference layer 306 is deposited on spacer layer 308, barrier layer 304 is deposited on reference layer 306, and free layer 302 is deposited on barrier layer 304.

Reference layer 306 may be plasma treated prior to depositing barrier layer 304 to smooth the surface of reference layer 306 or to reduce the surface roughness of reference layer 306 and enhance the quality of first TMR film 220. The reference layer 306 comprises CoFe/Ta/CoFeB/plasma treated/CoFe as a multilayer stack. The plasma treatment is performed at low power (e.g., about 35W) to slightly etch the amorphous CoFeB layer and make it smoother.

To form second TMR film 230, seed layer 414 is deposited, AFM layer 412 is deposited on seed layer 414, first pinning layer 410 is deposited on AFM layer 412, second spacing layer 418 is deposited on first pinning layer 410, second pinning layer 416 is deposited on second spacing layer 418, first spacing layer 408 is deposited on second pinning layer 416, reference layer 406 is deposited on first spacing layer 408, barrier layer 404 is deposited on reference layer 406, and free layer 402 is deposited on barrier layer 404.

The reference layer 406 may be plasma treated prior to depositing the barrier layer 404 to smooth the surface of the reference layer 406 or to reduce the surface roughness of the reference layer 406 and enhance the quality of the second TMR film 230. The reference layer 406 contains CoFe/Ta/CoFeB/plasma treated/CoFe as a multilayer stack. The plasma treatment is performed at low power (e.g., about 35W) to slightly etch the amorphous CoFeB layer and make it smoother.

Then, the first TMR film 220 and the second TMR film 230 may be heated in a magnetic oven simultaneously or separately at a temperature of about 250 degrees celsius to about 300 degrees celsius under a magnetic field of about 1 tesla to about 5 tesla. Then, first TMR film 220 and second TMR film 230 may be deposited on one or more bottom wirings. For example, first TMR film 220 may be deposited over first and second bottom leads, and second TMR film 230 may be deposited over third and fourth bottom leads. One or more top leads may then be formed over first TMR film 220 and second TMR film 230. For example, a first top lead may be formed over a first bottom lead, a second top lead may be formed over a second bottom lead, a third top lead may be formed over a third bottom lead, and a fourth top lead may be formed over a fourth bottom lead.

Fig. 5A to

5B show graphs

500, 550 of output signals of the first TMR film and the second TMR film, respectively, with an applied external field. Fig. 5A shows a graph 500 of the output signal or resistivity (R) of the first TMR film 220 of fig. 2 and 3B versus the applied external field (H). Fig. 5B shows a graph 550 of the output signal or resistivity (R) of the second TMR film 230 of fig. 2 and 4B versus the applied external field (H).

As shown in fig. 5A, the TMR resistance of the first TMR film increases linearly with the applied field. The magnetization direction 324 reference layer of the first TMR film is fixed and directed in the x direction. The magnetization direction 422 of the free layer rotates with increasing external field, pointing first in the x-direction, then in the y-direction, then in the x-direction.

As shown in fig. 5B, the TMR resistance of the second TMR film linearly decreases with the applied field. The magnetization direction 424 of the second TMR film reference layer is fixed and pointing in the x-direction. The magnetization direction 422 of the free layer rotates with increasing external field, pointing first in the x-direction, then in the y-direction, then in the x-direction.

Fig. 5A and 5B show that since first TMR film 220 and second TMR film 230 have different RL magnetization directions, the TMR resistance response of each film is equal but opposite (i.e., as the first TMR film increases linearly, the second TMR film decreases linearly).

Therefore, using the above TMR sensor device or wheatstone bridge design having four resistors composed of two different TMR films allows the magnetic sensor to operate in the full magnetoresistance range while achieving the maximum output voltage. By using a first TMR film for the first and fourth resistors and a second TMR film for the second and third resistors, the magnetoresistive response of the resistors is equal but opposite, thereby achieving a full bridge sensing scheme that achieves maximum sensitivity for a given TMR ratio.

In one embodiment, the TMR sensor is used in a camera operating as a single axis sensor. Examples of such sensors are found in U.S. patent application publication 2019/0020822 a1, which is incorporated herein by reference. However, it is contemplated that TMR sensors may be used as two-dimensional or even three-dimensional sensors. In addition, it is contemplated that TMR sensors may be integrated and used in inertial measurement unit technologies other than cameras, such as wearable devices, compasses, and MEMS devices. Further, the TMR sensor may operate as a position sensor, a bridge angle sensor, a magnetic switch, a current sensor, or a combination thereof. The TMR sensor may be used to focus a camera, such as a smartphone camera, by using the TMR sensor as a position and angle sensor. In addition, TMR sensors may also be used in the automotive industry as switches, current and angle sensors instead of current hall sensors, Anisotropic Magnetoresistive (AMR) sensors and Giant Magnetoresistive (GMR) sensors. TMR sensors may also be used as position and angle sensors in the unmanned aerial vehicle and robotics industries. The medical device may also utilize a TMR sensor for flow control of the infusion system, and may also utilize an endoscopic camera sensor or the like. Thus, the TMR sensor discussed herein has applications far beyond smart phone cameras, and therefore should not be limited to use as a sensor for smart phone cameras. Furthermore, the TMR sensors need not be arranged in a wheatstone bridge arrangement, but can be arranged in any number of ways.

The at least one TMR sensor constituted by the first TMR film includes a first TMR sensor and a fourth TMR sensor, and the at least one TMR sensor constituted by the second TMR film includes a second TMR sensor and a third TMR sensor. The first TMR sensor is adjacent to the second TMR sensor and the third TMR sensor, the second TMR sensor is adjacent to the first TMR sensor and the fourth TMR sensor, the third TMR sensor is adjacent to the first TMR sensor and the fourth TMR sensor, and the fourth TMR sensor is adjacent to the second TMR sensor and the third TMR sensor. The first TMR film further includes a first free layer, a first barrier layer, a first spacer layer, a first antiferromagnetic layer, and a first seed layer. A first barrier layer is disposed between the first reference layer and the first free layer, a first spacer layer is disposed between the first reference layer and the first pinned layer, and a first antiferromagnetic layer is disposed between the first pinned layer and the first seed layer.

The second TMR film further includes a second free layer, a second barrier layer, a second spacer layer, a third spacer layer, a second antiferromagnetic layer, and a second seed layer, and the second barrier layer is disposed between the second reference layer and the second free layer, the second spacer layer is disposed between the second reference layer and the third pinned layer, the third spacer layer is disposed between the second pinned layer and the third pinned layer, and the second antiferromagnetic layer is disposed between the second pinned layer and the second seed layer. The first TMR film has a total thickness of about 120 angstroms to about 630 angstroms, and wherein the second TMR film has a total thickness of about 155 angstroms to about 1675 angstroms. The Co composition in the CoFe of the Co/CoFe/Co multilayer stack of the first pinned layer is about 25% to 70%, wherein the B composition in the CoFeB of the CoFe/Ta/CoFeB/CoFe multilayer stack of the first reference layer is about 15% to 25%, wherein the Co composition in the CoFe of the Co/CoFe/Co multilayer stack of the second pinned layer is about 25% to 70%, and wherein the Co composition in the CoFe of the Co/CoFe/Co multilayer stack of the third pinned layer is about 25% to 70%.

The first TMR film further includes a first free layer, a first barrier layer, a first spacer layer, a first pinned layer, a first antiferromagnetic layer, and a first seed layer. A first barrier layer is disposed between the first reference layer and the first free layer, a first spacer layer is disposed between the first reference layer and the first pinned layer, and a first antiferromagnetic layer is disposed between the first pinned layer and the first seed layer. The second TMR film further includes a second free layer, a second barrier layer, a second spacer layer, a second pinning layer, a third spacer layer, a third pinning layer, a second antiferromagnetic layer, and a second seed layer. The second barrier layer is disposed between the second reference layer and the second free layer, the second spacer layer is disposed between the second reference layer and the third pinned layer, the third spacer layer is disposed between the second pinned layer and the third pinned layer, and the second antiferromagnetic layer is disposed between the second pinned layer and the second seed layer.

The third pinned layer of the second TMR film has a third magnetization direction parallel to the first magnetization direction of the first reference layer of the first TMR film. The first free layer of the first TMR film has a fourth magnetization direction parallel to the fifth magnetization direction of the second free layer of the second TMR film. The fourth magnetization of the first free layer of the first TMR film is parallel to the sixth magnetization direction of the first pinned layer of the first TMR film. The first pinned layer of the first TMR film comprises a Co/CoFe/Co multilayer stack having a thickness between about 20 angstroms to about 30 angstroms, wherein the second pinned layer of the second TMR film comprises a Co/CoFe/Co multilayer stack having a thickness between about 20 angstroms to about 30 angstroms, and wherein the third pinned layer of the second TMR film comprises a Co/CoFe/Co multilayer stack having a thickness between about 35 angstroms to about 55 angstroms, wherein the second pinned layer of the second TMR film has a thickness greater than the first pinned layer of the second TMR film. The first TMR film has a total thickness of about 120 angstroms to about 630 angstroms, and wherein the second TMR film has a total thickness of about 155 angstroms to about 1675 angstroms.

The first TMR film and the second TMR film are magnetically annealed in a magnetic oven at a temperature of about 250 degrees celsius to about 300 degrees celsius and a magnetic field of about 1 tesla to about 5 tesla. Forming the first and fourth resistors from the first TMR film includes depositing the first TMR film over first and second bottom leads, and forming a first top lead over the first bottom lead and a second top lead over the second bottom lead. Forming the second and third resistors from the second TMR film includes depositing the second TMR film over third and fourth bottom leads, and forming a third top lead over the third bottom lead and a fourth top lead over the fourth bottom lead. The first TMR film has a total thickness of about 120 angstroms to about 630 angstroms, and wherein the second TMR film has a total thickness of about 155 angstroms to about 1675 angstroms. The first resistor, the second resistor, the third resistor, and the fourth resistor are TMR sensors.

While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. A Tunneling Magnetoresistive (TMR) sensor device, the TMR sensor device comprising:

at least one TMR sensor including a first TMR film including a first reference layer having a first magnetization direction and a first pinned layer having a second magnetization direction, the first magnetization direction of the first reference layer being antiparallel to the second magnetization direction of the first pinned layer,

wherein the first pinned layer comprises a Co/CoFe/Co multilayer stack having a thickness of about 20 angstroms to about 30 angstroms, and

wherein the first reference layer comprises a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms; and is

At least one TMR sensor including a second TMR film including a second reference layer having a third magnetization direction, a second pinned layer having the third magnetization direction, and a third pinned layer having a fourth magnetization direction, the third magnetization directions of the second reference layer and the second pinned layer being antiparallel to the fourth magnetization direction of the third pinned layer,

wherein the second pinned layer comprises a Co/CoFe/Co multilayer stack having a thickness of about 20 angstroms to about 30 angstroms,

wherein the third pinned layer comprises a Co/CoFe/Co multilayer stack having a thickness of about 35 angstroms to about 55 angstroms, and

wherein the second reference layer comprises a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms.

2. The TMR sensor device of claim 1, wherein the at least one TMR sensor composed of the first TMR film includes a first TMR sensor and a fourth TMR sensor, and wherein the at least one TMR sensor composed of the second TMR film includes a second TMR sensor and a third TMR sensor.

3. The TMR sensor device of claim 2, wherein the first TMR sensor is adjacent to the second TMR sensor and the third TMR sensor, the second TMR sensor is adjacent to the first TMR sensor and the fourth TMR sensor, the third TMR sensor is adjacent to the first TMR sensor and the fourth TMR sensor, and the fourth TMR sensor is adjacent to the second TMR sensor and the third TMR sensor.

4. The TMR sensor device of claim 1, wherein the first TMR film further comprises a first free layer, a first barrier layer, a first spacer layer, a first antiferromagnetic layer, and a first seed layer, and wherein the first barrier layer is disposed between the first reference layer and the first free layer, the first spacer layer is disposed between the first reference layer and the first pinned layer, and the first antiferromagnetic layer is disposed between the first pinned layer and the first seed layer.

5. The TMR sensor device of claim 1, wherein the second TMR film further comprises a second free layer, a second barrier layer, a second spacer layer, a third spacer layer, a second antiferromagnetic layer, and a second seed layer, and

wherein the second barrier layer is disposed between the second reference layer and the second free layer, the second spacer layer is disposed between the second reference layer and the third pinned layer, the third spacer layer is disposed between the third pinned layer and the second pinned layer, and the second antiferromagnetic layer is disposed between the second pinned layer and the second seed layer.

6. The TMR sensor device of claim 5, wherein the first TMR film has a total thickness of about 120 angstroms to about 630 angstroms, and wherein the second TMR film has a total thickness of about 155 angstroms to about 1675 angstroms.

7. The TMR sensor device of claim 1, wherein the Co composition in CoFe of the Co/CoFe/Co multilayer stack of the first pinned layer is about 25% to 70%, wherein the B composition in CoFeB of the CoFe/Ta/CoFeB/CoFe multilayer stack of the first reference layer is about 15% to 25%, wherein the Co composition in CoFe of the Co/CoFe/Co multilayer stack of the second pinned layer is about 25% to 70%, and wherein the Co composition in CoFe of the Co/CoFe/Co multilayer stack of the third pinned layer is about 25% to 70%.

8. A TMR sensor device, comprising:

a first resistor comprising a first TMR film comprising a first reference layer having a first magnetization direction, wherein the first reference layer comprises a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms;

a second resistor comprising a second TMR film comprising a second reference layer having a second magnetization direction, wherein the second reference layer comprises a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms, and wherein the first magnetization direction of the first reference layer of the first TMR film is anti-parallel to the second magnetization of the second reference layer of the second TMR film;

a third resistor including the second TMR film; and

a fourth resistor including the first TMR film.

9. The TMR sensor device of claim 8, wherein the first TMR film further comprises a first free layer, a first barrier layer, a first spacer layer, a first pinned layer, a first antiferromagnetic layer, and a first seed layer,

wherein the first barrier layer is disposed between the first reference layer and the first free layer, the first spacer layer is disposed between the first reference layer and the first pinned layer, and the first antiferromagnetic layer is disposed between the first pinned layer and the first seed layer,

wherein the second TMR film further comprises a second free layer, a second barrier layer, a second spacer layer, a second pinning layer, a third spacer layer, a third pinning layer, a second antiferromagnetic layer and a second seed layer, and

10. The TMR sensor device of claim 9, wherein the third pinned layer of the second TMR film has a third magnetization direction parallel to the first magnetization direction of the first reference layer of the first TMR film.

11. The TMR sensor device of claim 9, wherein the first free layer of the first TMR film has a fourth magnetization direction parallel to a fifth magnetization direction of the second free layer of the second TMR film.

12. The TMR sensor device of claim 11, wherein the fourth magnetization of the first free layer of the first TMR film is parallel to a sixth magnetization direction of the first pinned layer of the first TMR film.

13. The TMR sensor device of claim 9, wherein the first pinned layer of the first TMR film comprises a Co/CoFe/Co multilayer stack having a thickness of about 20 angstroms to about 30 angstroms, wherein the second pinned layer of the second TMR film comprises a Co/CoFe/Co multilayer stack having a thickness of about 20 angstroms to about 30 angstroms, and wherein the third pinned layer of the second TMR film comprises a Co/CoFe/Co multilayer stack having a thickness of about 35 angstroms to about 55 angstroms.

14. The TMR sensor device of claim 13, wherein the first TMR film has a total thickness of about 120 angstroms to about 630 angstroms, and wherein the second TMR film has a total thickness of about 155 angstroms to about 1675 angstroms.

15. A method of manufacturing a TMR sensor device having a first resistor, a second resistor, a third resistor, and a fourth resistor, the method comprising:

forming a first TMR film by:

a first seed layer is deposited on the substrate,

depositing a first antiferromagnetic layer on the first seed layer,

depositing a first pinning layer on the first antiferromagnetic layer, the first pinning layer comprising a Co/CoFe/Co multilayer stack having a thickness of about 20 angstroms to about 30 angstroms,

depositing a first spacer layer over the first pinned layer,

depositing a first reference layer over the first spacer layer, the first reference layer comprising a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms,

depositing a first barrier layer on the first reference layer, and

depositing a first free layer on the first barrier layer;

magnetically annealing the first TMR film to change a first magnetization direction of the first reference layer to be antiparallel to a second magnetization direction of the first pinned layer;

forming a second TMR film by:

a second seed layer is deposited on the substrate,

depositing a second antiferromagnetic layer on the second seed layer,

depositing a second pinning layer on the second antiferromagnetic layer, the second pinning layer comprising a Co/CoFe/Co multilayer stack having a thickness of about 20 angstroms to about 30 angstroms,

depositing a second spacer layer on the second pinning layer,

depositing a third pinning layer on the second spacer layer, the third pinning layer comprising a Co/CoFe/Co multilayer stack having a thickness of about 35 angstroms to about 55 angstroms,

depositing a third spacer layer on the third pinning layer,

depositing a second reference layer comprising a CoFe/Ta/CoFeB/CoFe multilayer stack having a thickness of about 21 angstroms to about 37 angstroms over the third spacer layer,

depositing a second barrier layer on the second reference layer, and

depositing a second free layer on the second barrier layer;

magnetically annealing the second TMR film to change a third magnetization direction of the third pinned layer to be antiparallel to a fourth magnetization direction of the second reference layer, wherein the first magnetization direction of the first reference layer of the first TMR film is antiparallel to the fourth magnetization direction of the second reference layer of the second TMR film;

forming the first resistor and the fourth resistor from the first TMR film; and is

Forming the second resistor and the third resistor from the second TMR film, wherein the first resistor is adjacent to the second resistor and the third resistor, the second resistor is adjacent to the first resistor and the fourth resistor, the third resistor is adjacent to the first resistor and the fourth resistor, and the fourth resistor is adjacent to the second resistor and the third resistor.

16. The method of claim 15, wherein the first TMR film and the second TMR film are magnetically annealed in a magnetic oven at a temperature of about 250 degrees celsius to about 300 degrees celsius and a magnetic field of about 1 tesla to about 5 tesla.

17. The method of claim 15, wherein forming the first and fourth resistors from the first TMR film includes depositing the first TMR film over first and second bottom leads, and forming a first top lead over the first bottom lead and a second top lead over the second bottom lead.

18. The method of claim 15, wherein forming the second and third resistors from the second TMR film includes depositing the second TMR film over third and fourth bottom leads, and forming a third top lead over the third bottom lead and a fourth top lead over the fourth bottom lead.

19. The method of claim 15, wherein the first TMR film has a total thickness of about 120 angstroms to about 630 angstroms, and wherein the second TMR film has a total thickness of about 155 angstroms to about 1,675 angstroms.

20. The method of claim 15, wherein the first, second, third, and fourth resistors are TMR sensors.